Journal of the Society of Motion Picture Engineers (1930-1949)

Record Details:

Title:
Journal of the Society of Motion Picture Engineers
Date:
1930-1949
Publisher:
New York, N.Y. : The Society
Volume:
Journal of the Society of Motion Picture Engineers
Leaf #:
000418
Language:
English
Collection:
Technical Journals
Format:
Periodicals
Contributor:
Prelinger Library
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
The Journal of the Society of Motion Picture Engineers (SMPE)Êdocuments the technological progress of the film industry, highlighting technical developments in production and exhibition. Of special interest are articles about special effects, theater practices, lighting, and the introduction of the 16mm format. Initially titled "Transactions of the Journal of the Society of Motion Picture Engineers."Digitized by the Prelinger Library and the Library of Congress Motion Picture, Broadcasting and Recorded Sound Division.
Date Added:
July 19, 2022
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1949 ARC SPOTLIGHT 415 Now we wish to find the distance d between the two lenses, so by observation (Fig. 5) Substituting (2) and (3) we obtain !/„/„ d = /2 d + ui = Mi5 2 -ft (4) (5) Therefore for any distance u\ of the small lens, and a known projection distance F2, we can readily calculate the position of the large lens to obtain a sharp, clear-cut spot. s v2 Fig. 5 — Lens optical system. F2 t/2 focal length of small lens. A object distance for small lens. D image distance for small lens. S focal length of large lens. / object distance for large lens. R aperture diameter, distance between lenses, diameter of projected spot, virtual image, reflector. image distance for large lens. It is evident that the small lens creates a virtual image of the aperture. The large lens focuses on this virtual image and projects it to the desired location. Table I shows the various distances of the large lens from the aperture as the small lens distance is varied. For these calculations the projected throw (F2) is 60 feet. TABLE I u\, Inches d + Ui, Inches ui, Inches d + ui, Inches 0 18.47 1.50 16.22 0.25 18.44 1.75 14.39 0.50 18.34 2.00 10.47 0.75 18.15 2.125 6.43 1.00 17.80 2.160 4.75 1.25 17.22 2.1875 3.12